Another method I see used alot in both the iOS and Android version is using Youtube to mp3 converters. There are a bunch of fly-by-night websites for the task, but they turn out pretty risky with advertisements and virus potential.
There is a pretty good free app for PC (Not Android) called "FreeMake YouTube to MP3 Boom"
http://www.freemake.com/free_youtube_converter/It lets you search for titles, listen to make sure it is what you want and then a download button which puts the file in your PC music folder. Find the file there, email it to yourself, open the email on your device, tap the attachment, open with Walkout Songs and it should be there in your import files list.